1. Field of the Invention
The present invention relates to the field of preparing and handling of doses of liquids, thereby of very small doses down to e.g., some hundreds of nano-liters with accurately predetermined volumes. Such liquid handling techniques are especially used in context with medical, chemical or biochemical analyses, e.g., in pharmaceutical, medical or food industry laboratories.
2. The Prior Art
Thereby, it is of utmost importance to aspire, as probes e.g. to be analyzed, small samples of liquids of accurately known volumes and often at a high rate. Latter may be important e.g. in context with blood analyses of large populations, as become necessary to rapidly track out-braking contagious illnesses.
It is known to aspirate liquids from multiple receptacles by pipettes. The pipettes are thereby conveyed to and aligned with receptacles, lowered so as to be dipped in the respective liquids in the receptacles. To each pipette there is associated a valve- and a pumping-arrangement. By respective control of the valves and of the pumping arrangements, each pipette aspirates the respective dose of liquid from the receptacle. So as to ascertain that the volumes of the aspirated doses—the samples—accurately accord with the predetermined, rated volumes, with deviations of only few percentages, high demands must be fulfilled by the pumping arrangement, by the valves and by the respective controls.
We understand under a “rated” volume of a dose, the volume of a dose which is desired. A dose as produced should, ideally, have a volume equal to the rated volume.
The doses of liquids once aspirated into the pipettes are customarily conveyed within the pipettes to a destination location where they are released from the pipettes by respective controls of the valves and pumping arrangements.
Subsequently the pipettes can be rinsed with a rinsing solution, if necessary.
The aspiration steps are performed in that all valves and pumping arrangements, each associated to one pipette, are operated simultaneously or staggered in time.
It is an object of the present invention to provide an alternative pipetting arrangement and an alternative method of controlling a pipetting arrangement or of producing liquid product doses.